What you may notice
When urine cannot drain freely from a kidney, its collecting system can swell. This is called hydronephrosis. It may cause flank or back pain, nausea, urinary changes or fever, but some blockages are painless and found on a scan.
Kidneys, ureters and bladder
What could cause it?
Stones, narrowing from scarring, a tumour, an enlarged prostate or pressure from nearby structures can obstruct drainage. Infection can coexist. Not every widened collecting system means an active blockage, and muscle pain can resemble kidney pain. Urine and blood tests, ultrasound and selected additional imaging assess drainage and kidney function.
When to contact a doctor
A reported obstruction needs prompt review. Fever or shivering with a blocked kidney, severe persistent pain, vomiting or greatly reduced urine needs urgent hospital assessment. The threshold is especially low with one functioning kidney. Confusion, collapse or severe illness is an emergency: call 108.
How interventional radiology may help
A urological stent or an image-guided nephrostomy can bypass a suitable obstruction. A nephrostomy drains through the skin to an external bag; it may be temporary while the cause is treated. Urgent drainage may be needed for an infected obstruction. IR drainage does not itself remove every stone or cure a tumour, so further treatment and tube care are planned together.
Further reading: detailed assessment and treatment options
Patient information sources
References are in English.
Educational information, not a diagnosis. The causes listed are examples, not a complete list. Tests and treatment depend on your individual assessment.